Haul-a-Day underack bag fits into a space that other bikes do not! Under the Haul-a-Days rear rack is a sizable hidden space above the fender. This custom made for the Haul-a-Day bag is a huge 450 cubic inches that uses this hidden spce. It has a large Orange and White reflective stripe on the rear end. The Under rack bag features a loop for attaching your blinky rear light. This space is not only large but great to keep stuff that you might need completely out of your way. Bags fits with the BionX battery in place also.